Treatment of hydrocarbon oils



Patented Aug. 7, 1934 TREATMENT OFHYDROCARBON 011s Jacqiie C. Morrell,Chicago, Ill., assignor to Universal Oil Products Company, Chicago,111., a corporation of South Dakota No Drawing. Application December 19,1931, Serial No. 582,152

3 Claims.

This invention relates to the treatment of hydrocarbon oils and moreparticularly is directed to the treatment of petroleum distillates,especially those resulting from the conversion of 5 relatively higherboiling hydrocarbons into lower I like,

,cracking process. I

boiling hydrocarbons by treatment at elevated temperatures, commonlyreferred to as cracked distillates, by subjecting the same while invapor form to the action of solutions of acid sulphates alone or indirect combination with sulphuric acid. More particularly, the inventionrelates to the treatment of the said hydrocarbons while in the vaporform with solutions containing sulphuric acid and a salt of an alkalineearth metal such as the sulphates of calcium, barium, magnesiumandstrontium. Presumably, these salts .are present as acid sulphates andit is desirable .that they always be present in the form of the acidsulphate, i. e. with excess sulphuric acid. Where an insuflicientquantity of the sulphate of the alkaline earth is dissolved to controlthe concentration of the sulphuric acid, the sulphates or acid sulphatesof the alkali metals such as sodium, potassium and ammonium may be addedin addition.

Petroleum distillates, especially cracked distillates, containundesirable compounds, presumably of a highly unsaturated charactenwhichrender them unstable with respect to color, gum forming properties andknock rating. Such distillates tend to deposit polymer or gum -likesubstances while in storage, causing a drop in color which may renderthe product unsaleable. The development of gums may also prevent properoperation of the motor by plugging or gumming up the fuel feed lines,carburetor, valves and other parts of the motor.

I Other objectionable compounds such as those of sulphur, nitrogen andthe may be present in such distillates, and it is among the objects ofthis invention to remove or reduce to a minimum, the objectionablesubstances present in hydrocarbons and more particularly, in petroleumdistillates. I

. One of the most important and most desirable developments in petroleumrefining is the direct production of a marketable distillate from theMany attempts have been made to employ refining agents for this purpose,particularly directed towards the use of sulphuricacid which for themost part have been unsuccessful because they have failed to take intoconsideration the physical and chemical properties of sulphuric acidunder the conditions of rein the United States, but heretofore, it hasbeen most successfully applied as arefining agent to petroleum and itsproducts while in the liquid state. 1 The following table taken from1913 Edition of the Manufacture of Sulphuric Acid and Alkali by Lunge, astandard work on the subject, shows the relationship between the boilingpoint and con centration of sulphuric acid:

Table 1 msoi B. Pt. r.

From the above table it is evident that vat a given temperature and'ateach temperature, the sulphuric acid exists at a definite concentrationand that irrespective of the concentration ofthe sulphuric acid feedinto a system ata given temperature, if it is more dilute than thatindiecated by the concentration for the corresponding temperature itwill concentrate to the givenconcentration. For example, if anapproximately 8% solution of sulphuric acid is fed into a tower, theaverage temperature of which is approximately 360 R, neglecting thepartial pressures of the steam and oil vapors, the sulphuric acidintroduced will concentrate to approximately and under thesetemperatures, such a concentration of sulphuric acid will immediatelyattack and destroy the unsaturated hydrocarbons in the immediatevicinity, resulting in an offcolored overhead product of high gumcontent and in a charring of the derivatives of sulphuric acid in thehydrocarbons, plugging up the column and rendering the processinoperatiye. The

above indicates only approximately the conditions existing in the tower,but is sufficient to illustrate the trend and direction of the reactionand explain why previous attempts to refine in the manner described,have been unsuccessful. It is well known that concentrations ofsulphuric acid which maybe even substantially non-reactive at ordinarytemperatures are highly destructive in their reactions at elevatedtemperatures. Hence, while it is desirable to treat petroleumdistillates in the vapor state in order to avoid the expense ofredistilling the product, it isimperative that a method of treatment beprovided which will enable one to definitely control the concentrationand consequentlyth'e rate of reraction and kind of reaction at theelevated temperatures of treatment.

scribed.

In a specific aspect the invention comprises treating hydrocarbonvapors, especially cracked hydrocarbon vapors, with an aqueous solutioncontaining dissolved therein sulphuric acid and a; sulphate of a analkaline earth metal which is presumably present in the form of the acidsulphate. r v M In effecting the'operation of the invention, hydrocarbonvapors from any source, for example, direct from a cracking process, andin general from a distillation process, including vapors fromatmospheric distillation or hydrocarbon vapors from rerun stills, may bepassed counter-current or concurrent to the solution containing the acidsulphate and the sulphuric acid. The treating solution may be introducedin the form of a spray, atomized or otherwiseintroduced and employed insuch manner as to give the most chicient contact of treating agent andvapors undergoing treatment. Under some conditions, the hydrocarbonvapors may be bubbled through a pool or pools of the treating agentpreferably feeding in fresh reagent and withdrawing sludge continuously.In the countercurrentoperation the vapors may be withdrawn from the topof the treating tower and maybe condensed or fractionated and condensed,preferably subjecting the treated hydrocarbons to treatment with alkalisor combination washing and alkali to remove sulphur dioxide and possiblysome' entrained treating agent. In the concurrent method of operationthe vapors, reflux condensate and sludge may be passed through aseparator, withdrawing the vaporsand condensing as described, andseparatelywithdrawing the sludge and/orpro'ducts of reaction togetherwith unused treating agent and reflux condensate if present. Steam maybe introduced into the column duringlthetreathient in order to maintainan equilibriiiin between the dissolved substances in. the ivatfer,namely, the acid sulphate and sulphuric acid.

' The sludge may be used directly by recirculating to the treatingcolumn, The acid sulphates may be recovered 'by dilution and treatmentof the slud e with water and subsequent purification and evaporation ofthe solution.

The process may constitute the solestep of the process in the refiningof they hydrocarbons or may be combi'nedwith other treatments eitherapplied before or after the process ofthis invention; For example,thevapors from the treating tower may be subsequently passed through afllter or series of filterscontaining inert filter ing agents,adsorbents, solid alkalis, such as lime,

The: present invention accomplishes this aim in a new and novel man-'-ner which will be hereinafter more fully decaustic or mixtures of theseand the like, catalytic materials such as metals and metallic oxides,solutions of alkalis, and the like. Preferably the vapors arefractionated before passing to the treating stage and may befractionated after passing to the treating stage. Prior ,treatments ofthe hydrocarbons with other reagents, either in the vapor or liquidphase, or subsequent treatment of the condensed liquid may be applied.

For example, the condensed product may be sweetened by treatment withplumbite solutions, solutions of copper salts or other metallic saltsalone or in combination with auxiliary chemical treatments with acids,and the like or with filtering agents such as fullers earth and likeadsorbing agents. Sludges from the treating reagent may be reused orregenerated.

As specific examples of reagents used in the present invention wherecalcium sulphate is employed, an approximately 4% solution'in a 10%solution of the sulphuric acid may be employed. A solution containingapproximately 18% of barium sulphate and approximately of sulphuric acidmay be employed. Strontium sulphatefwill give a similar solution andmagnesium sulphate Will dissolve to a greater extent. For someconditions of treatment the alkaline earth'metals, sulphates orequivalent salts do not dissolve-to a sufficient extent to permitthe-requiredcon- 365 trol of the concentration of the sulphuricacidunder the conditions of treatment.-

In order to obtain exact control of'the-solution, it is preferred inmany cases to-ad'd-to'the sulphuricacid a sulphate or acid sulphate,p'ar- 1-10 ticularly a sulphate of-the-alkalimetals suchas sodium;potassium orammonium sulphate,-- in addition 'to the sulphates of thealkaline earth metals. Generally, the initial concentrations ofsulphuric acid employed, vary from-30;to 60% 1'15 and theinitial-concentrations of salts employed vary from -5 to 20%,theremainder being water.

As an example of results obtainableby the operation-of the process of myinvention,- and of the operating conditions thereof, the 'follow 120 ingmay-be cited; A California crack'eddistillate containing approximately0.45 sulphuri's subjected 'to' treatment the vapor form at approximately300 F; with a solution containing approximately 50 of calciumsulphate,15% of ammonium acid sulphate and 25% of water." I The resultant productmay have a'color of approximately '28which is stable on-exp'osure tosunlight, a g-umcontent of; sulphuric acid, 10%

ofapproxi-mately 15 "mgs. per'100fcc. and' 'a l iid Mixtures of 1. In aprocess for the refining of hydrocarbon oils, the improvement whichcomprises subjecting. the said hydrocarbon oils while 'inheated vaporouscondition to reaction with an aqueous solution of sulphuric acid-inwhich has'been' dissolved atleast 4% of "a sulphate of an alkali lbometal, the amount of acid originally contained in the solution exceedingthe amount of the sulphate added thereto.

2. In a process for the refining of cracked hydrocarbon oils, theimprovement which comprises subjecting the said cracked hydrocarbon oilsin heated vaporous condition to reaction with an aqueous solution ofsulphuric acid in which has been dissolved at least 4% of a sulphate ofan alkaline earth metal and a sulphate of an alkali metal, the amount ofacid originally con- J ACQUE C. MORREIL.

